Some Ideas I had:
-Feature that tracks hours studying, on review or cram or whatever
-Cram gives you xp
-Have the option to draw the kanji yourself (tablet or the like) to understand it better,
-Have the option to switch between reading in English and trying to translate it to japanese, and the same thing with vocab.
Don’t know if this is the place to suggest this but im pretty positive a lot of people would enjoy these features. PLS add to this if you have any other ideas,